Tubificid worms have been shown to be quite tolerant to toxic materials such as lead, phenol, and zinc. Their median tolerance limit (Tlm) for pH levels in modified Knop solution has been shown to be 5.8 to 9.7. Their Tlm for lead was 49.0 pp, at pH 6.5 and 27.5 at a pH of 8.5. For sodium pentochlorophenate (PCP) the Tlm was found to be 0.31 ppm at pH 7.5, 0.67 ppm at pH 8.6 and 1.4 ppm at pH 9.5. The Tlm determined for zinc was 46.0 ppm at pH 7.5. The interactions of pH and these substances has been examined and discussed, and the importance of definition of the solution has been shown. The mechanism of toxicity for lead and zinc probably is the mucousmetal complex which precipitates on the body wall blocking the exchange of oxygen and carbon dioxide. This is similar to the reaction of these metals observed in the gills of fish. The toxic mechanism of PCP is possibly a biochemical interruption of oxidative phosphorylation. It is not a mucous-effecting mechanism because no mucous precipitate forms as with the metals. In each instance these experiments show tubificids with a quantitative resistance to lead, zinc and phenol greater than similar resistance recorded for various fish species. This provides a basis for quantitative evaluation of the resistant nature of these organisms that may be valuable in future studies of their association to polluted habitats.
- 1 - sciences appliquees, technologies et medecines
- 2 - sciences biologiques et medicales
- 3 - sciences biologiques fondamentales et appliquees. psychologie